title: Genome analysis of Chitinivibrio alkaliphilus gen. nov., sp. nov., a novel extremely haloalkaliphilic anaerobic chitinolytic bacterium from the candidate phylum Termite Group 3.
abstract: Anaerobic enrichments from hypersaline soda lakes with chitin as substrate yielded five closely related anaerobic haloalkaliphilic isolates growing on insoluble chitin by fermentation at pH 10 and salinities up to 3.5 M. The chitinolytic activity was exclusively cell associated. To better understand the biology and evolutionary history of this novel bacterial lineage, the genome of the type strain ACht1 was sequenced. Analysis of the 2.6 Mb draft genome revealed enzymes of chitin-degradation pathways, including secreted cell-bound chitinases. The reconstructed central metabolism revealed pathways enabling the fermentation of polysaccharides, while it lacks the genes needed for aerobic or anaerobic respiration. The Rnf-type complex, oxaloacetate decarboxylase and sodium-transporting V-type adenosine triphosphatase were identified among putative membrane-bound ion pumps. According to 16S ribosomal RNA analysis, the isolates belong to the candidate phylum Termite Group 3, representing its first culturable members. Phylogenetic analysis using ribosomal proteins and taxonomic distribution analysis of the whole proteome supported a class-level classification of ACht1 most probably affiliated to the phylum Fibribacteres. Based on phylogenetic, phenotypic and genomic analyses, the novel bacteria are proposed to be classified as Chitinivibrio alkaliphilus gen. nov., sp. nov., within a novel class Chitinivibrione.
authors.affiliation: Winogradsky Institute of Microbiology, Russian Academy of Sciences, Prospect 60-let Oktyabrya, bld. 7-2, 117312, Moscow, Russia; Department of Biotechnology, Delft University of Technology, Delft, The Netherlands.
authors.forename: Dimitry Y
authors.initials: DY
authors.lastname: Sorokin
authors.forename: Vadim M
authors.initials: VM
authors.lastname: Gumerov
authors.forename: Andrey L
authors.initials: AL
authors.lastname: Rakitin
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Beletsky
authors.forename: J S Sinninghe
authors.initials: JS
authors.lastname: Damsté
authors.forename: Gerard
authors.initials: G
authors.lastname: Muyzer
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Mardanov
authors.forename: Nikolai V
authors.initials: NV
authors.lastname: Ravin
mesh_terms: D000693:Anaerobiosis; D000818:Animals; D001483:Base Sequence; D002686:Chitin / Q000378:metabolism; D061306:Fibrobacteres / Q000145:classification / Q000166:cytology / Q000235:genetics*; D016680:Genome, Bacterial; D006863:Hydrogen-Ion Concentration; D020049:Isoptera / Q000382:microbiology; D058889:Molecular Typing; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D012336:RNA, Ribosomal, 16S; D002686:Chitin